Do Clinical Correlates of Knee Osteoarthritis Predict Outcome of Intraarticular Steroid Injections?

Abstract

To determine whether clinical correlates of knee osteoarthritis (OA) affect the outcome of intraarticular steroid injections (IASI) in symptomatic knee OA. Men and women aged ≥ 40 years with painful knee OA who participated in an open-label trial of IASI completed questionnaires and clinical examination. The Outcome Measures in Rheumatology (OMERACT)-Osteoarthritis Research Society International (OARSI) criteria were used to assess response to therapy in the short term (within 2 weeks). Among those who initially responded, those whose pain had not returned to within 20% of the baseline Knee Injury and Osteoarthritis Outcome Score pain score at 6 months were characterized as longer-term responders. Log-binomial regression was used to examine factors associated with outcome. One hundred ninety-nine participants were included, of whom 146 (73.4%) were short-term and 40 (20.1%) longer-term responders. Compared to short-term nonresponders, participants with these characteristics were more likely to be short-term responders: medial joint line tenderness [relative risk (RR) 1.42, 95% CI 1.10-1.82], medial and lateral joint line tenderness (RR 1.38, 95% CI 1.03-1.84), patellofemoral tenderness (RR 1.27, 95% CI 1.04-1.55), anserine tenderness (RR 1.27, 95% CI 1.06-1.52), and a belief that treatment would be effective [RR/unit increase (range 0-10) = 1.05 (1.01-1.09)]. Aspiration of joint fluid (RR 0.79, 95% CI 0.66-0.95) and previous ligament/meniscus injury (RR 0.63, 95% CI 0.44-0.91) were associated with a reduced risk of being a short-term responder. Compared to initial nonresponders and those whose pain recurred within 6 months, participants with a higher number of pain sites [RR/unit increase (range 0-10) = 0.83, 95% CI 0.72-0.97], chronic widespread pain (RR 0.32, 95% CI 0.10-0.98), perceived chronicity of disease [RR/unit increase (range 0-10) = 0.86, 95% CI 0.78-0.94], and a higher depression score [RR/unit increase (range 0-21) = 0.89, 95% CI 0.81-0.99] were less likely to be longer-term responders. Among patients with symptomatic knee OA, tenderness around the knee was associated with better short-term outcome of IASI. However, clinical-related factors did not predict longer-term response, while those with chronic widespread pain and depressive symptoms were less likely to obtain longer-term benefits.